Method, apparatus, and electrolytic solution for electropolishing metallic stents

ABSTRACT

An apparatus, a method, and an electrolytic solution are described for electropolishing metallic stents made, for example, of high-strength medical alloys. The apparatus may include an electropolishing container made from material of low thermal conductivity. The apparatus may include at least one spiral cathode for optimization of solution agitation and/or voltage distribution in the electrolytic solution. Further, an electrolytic solution including at least dimethylsulfate is described. A method for improved electropolishing to consistently produce smooth surfaces is also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of International ApplicationNo. PCT/EP2010/000216 filed on 15 Jan. 2010, which claims the benefit ofU.S. Provisional Patent Application No. 61/145,453 filed on 16 Jan.2009. This application is also a continuation-in-part of InternationalApplication No. PCT/EP2010/000217 filed on 15 Jan. 2010, which claimsthe benefit of U.S. Provisional Patent Application No. 61/145,460 filedon 16 Jan. 2009. This application also claims priority to EuropeanPatent Application No. ______ filed on 15 Jul. 2010 entitled “Method andElectrolytic Solution for Electropolishing Stents Made of High StrengthMedical Alloys” having Attorney Docket No. AB01P068EP. Each of theforegoing applications is hereby incorporated herein, in its entirety,by this reference.

BACKGROUND

The present disclosure relates generally to providing an apparatus, amethod, and an electrolytic solution for electropolishing products madefrom metals. In particular, the present disclosure relates generally toelectropolishing metallic medical devices (e.g. stents) made ofhigh-strength medical alloys, such as stainless steel, titanium,nickel-titanium, tungsten, tantalum, niobium, cobalt-chromium,cobalt-chromium-tungsten, etc. While the apparatus, method, andelectrolytic solution are described herein as being applicable mainly tomedical stents, in particular intravascular stents, the disclosure isnot limited to such medical products. For example, the methods may beapplied to electropolish metallic automotive or aerospace components.

Stents are generally tube-shaped devices placed within a blood vessel orother body lumen to maintain the patency of the lumen and, in somecases, to reduce the development of restenosis. The stents may be formedin a variety of configurations which are typically expandable since theyare delivered in a compressed form to a desired site. Such aconfiguration may be a helically wound wire, wire mesh, weaved wire,serpentine stent, chain of rings, other configuration, or combinationsthereof. The walls of stents are typically perforated in a frameworkdesign of wire-like connected elements or struts, or in a weave designof cross-threaded wire.

Some stents are made of more than one material. For example, a stent mayinclude a sandwich of metals having outer layers of a biocompatiblematerial, such as stainless steel or cobalt-chromium, with an innerlayer providing the radiopacity to the stent for tracking by imagingdevices during placement. A stent made of such material may be, forexample, a thin layer of titanium between layers of stainless steel orcobalt-chromium. In forming such stents from metal, a roughened outersurface of the stent may result from the manufacturing process. It maybe desirable for the surface of the stent to be smooth so that it may beinserted and traversed with reduced friction through the blood vesselsor other body lumens toward the site of implantation. A rough outersurface may not only increase frictional obstruction, but may alsodamage the lining of the vessel wall during insertion. Furthermore,smooth surfaces may reduce thrombus formation and/or corrosion.

Since processing to form metallic stents often results in a productinitially having burrs, sharp ends, debris, slag material from meltingthe metal during processing, other features, or combinations thereof, asa first order treatment of the product, the surface may be descaled inpreparation for, for example, further surface treatment such aselectropolishing.

An apparatus, a method, and an electrolytic solution is provided forelectropolishing stents after they have been descaled, for example, asdisclosed in U.S. patent application Ser. No. 11/370,642 filed on 7 Mar.2006, the disclosure of which is hereby incorporated, in its entirety,by this reference.

Descaling may include, for example, dipping the stent into a stronglyacidic solution and/or ultrasonically cleaning the stent.

Electropolishing is an electrochemical process by which some of thesurface metal may be electrolytically dissolved. In general, the metalstent serves as an anode and is connected to a power supply whileimmersed in an electrolytic solution having a metal cathode connected tothe negative terminal of the power supply. Current flows from the stent,as the anode, causing it to become polarized. The rate at which themetal ions on the stent are dissolved may be controlled by the appliedcurrent and/or voltage. The positioning of the cathode relative to thestent may provide an even distribution of current to the stent.According to the theory of electropolishing, the current density istypically highest at high points protruding from a surface and istypically lowest at the surface low points. Thus, the higher currentdensity at the raised points may cause the metal to dissolve faster atthese points, which may level the surface. Electropolishing thereforemay smooth the surface, even to the point where it is shiny andreflective.

The present disclosure provides an apparatus, a method, and anelectrolytic solution for electropolishing a plurality of metallicdevices (e.g., stents) substantially simultaneously to consistentlyproduce smooth surfaces.

SUMMARY

The present disclosure is directed to an apparatus, a method, and anelectrolytic solution for electropolishing one or more metallic devices,such as metallic stents. An embodiment of an apparatus is provided forsubstantially simultaneously electropolishing a plurality of metallicstents. The apparatus may include a plurality of elongated members eachhaving a longitudinal axis, an electrolytic solution, a substantiallycontinuous cathode, a cathode current conducting member, and an anodecurrent conducing member. Each of the elongated members may include anelectrically conductive adaptor configured to be removably affixed toand in electrical contact with a metallic stent. The substantiallycontinuous cathode may be configured to be located in close proximity toeach of the elongated members when the elongated members andsubstantially continuous cathode are immersed in the electrolyticsolution. The cathode current conducting member is attached to thesubstantially continuous cathode, and each of the elongated members isconductively connected electrically with the anode current conductingmember.

In one embodiment, the substantially continuous cathode has a spiralconfiguration and/or the electrolytic solution is contained in acontainer made from non-metallic material. The container may be madefrom glass, ceramic, plastic, or other materials.

In another embodiment, the apparatus includes a second substantiallycontinuous cathode configured to be located in close proximity to eachof the elongated members when the elongated members and cathode areimmersed in the electrolytic solution and a second cathode currentconducting member attached to the second substantially continuouscathode.

In a further embodiment, the two cathodes are both in the shape of aspiral and are disposed substantially concentrically in the solution.

An embodiment of a method is also provided for electropolishing at leastone metallic stent. The method may include:

a) affixing a stent onto a corresponding one of one or more electricallyconductive adaptors of an apparatus, the apparatus including:

-   -   one or more elongated members having a longitudinal axis, each        of the members including an electrically conductive adaptor        configured to be removably affixed to and in electrical contact        with a metallic stent;    -   an electrolytic solution;    -   a substantially continuous cathode configured to be located in        close proximity to each of the elongated members when the        elongated members and the substantially continuous cathode are        immersed in the electrolytic solution;    -   a cathode current conducting member attached to the        substantially continuous cathode;    -   an anode current conducting member, wherein each of the        elongated members is conductively connected electrically with        the anode current conducting member;

b) immersing the stent(s) into the electrolytic solution;

c) supplying a voltage difference between the cathode current conductingmember and the anode current conducting member; and

d) removing the stent(s) from the solution and rinsing with at least onerinsing solution.

In one embodiment, the method further may include

e) removing the stents from the apparatus;

f) rinsing the stents;

g) immersing the stents in a passivation solution;

h) removing the stents from the passivation solution and rinsing;

i) placing the stents in a liquid and applying ultrasound energy to theliquid, or combinations thereof.

In another embodiment, in act c) the voltage is supplied for a period inthe range of about 20 to about 60 seconds while the stents are immersedin the electrolytic solution.

In a further embodiment, acts b), c), and d) are repeated three to fivetimes.

In one embodiment, the passivation solution includes nitric acid.

In one embodiment, the electrolytic solution comprises at leastdimethylsulfate. In some embodiments, the electrolytic solution may notinclude polyethylene glycol, dimethylsulfate, and ethanol at the sametime. In other embodiments, the electrolytic solution may includepolyethylene glycol, dimethylsulfate, and ethanol. In other embodiments,the electrolytic solution includes polyethylene glycol, dimethylsulfate,ethanol, and methanol.

In a further embodiment, the electrolytic solution may further includeat least one additional component, such as at least one alcohol. Forexample, the at least one alcohol may be a polyol (e.g., polyethyleneglycol) and/or at least one alkyl alcohol (e.g., ethanol, methanol, ormixtures thereof).

In one embodiment, the electrolytic solution may include from about 25to about 60 weight percent dimethylsulfate, from about 30 to about 40weight percent dimethylsulfate, from about 35 to about 39 weight percentdimethylsulfate, or about 37 weight percent dimethylsulfate.

In another embodiment, the electrolytic solution may include from about40 to about 70 weight percent dimethylsulfate, from about 50 to about 60weight percent dimethylsulfate, from about 54 to about 58 weight percentdimethylsulfate, or about 55 to about 57 weight percent dimethylsulfate.

In one embodiment, the electrolytic solution further comprisespolyethylene glycol. The electrolytic solution may include from about0.1 to about 5 weight percent polyethylene glycol, from about 0.5 toabout 2 weight percent polyethylene glycol, or about 0.5 to about 1weight percent polyethylene glycol. In a further embodiment, thepolyethylene glycol is PEG 1000. The electrolytic solution may includepolyethylene glycol in any of the disclosed weight percentages alongwith dimethylsulfate in any of the disclosed weight percentages.

When the electrolytic solution further comprises at least one alkylalcohol (e.g., ethanol, methanol, or mixtures thereof), the electrolyticsolution may include from about 15 weight percent to about 50 weightpercent ethanol, from about 20 to about 40 weight percent ethanol, fromabout 25 to about 35 weight percent ethanol, or about 28 weight percentethanol. In one embodiment, the balance of the electrolytic solutioncontaining at least one alkyl alcohol (e.g., ethanol) is made up ofmethanol.

These and other objects and features of the present disclosure willbecome more fully apparent from the following description and appendedclaims, or may be learned by the practice of the disclosure as set forthhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of thepresent disclosure, a more particular description of the disclosure willbe rendered by reference to specific embodiments thereof which areillustrated in the appended drawing. It is appreciated that this drawingdepicts only illustrated embodiments of the disclosure and are thereforenot to be considered limiting of its scope. The disclosure will bedescribed and explained with additional specificity and detail throughthe use of the accompanying drawing in which:

FIG. 1 is a diagrammatic view of an electropolishing apparatus showingat least one stent immersed in an electrolytic solution and in closeproximity to the cathode according to an embodiment of the presentdisclosure.

DETAILED DESCRIPTION

The present disclosure is directed to an apparatus, a method, and anelectrolytic solution for electropolishing one or more metallic devices,such as metallic stents. One or more embodiments of the presentdisclosure may advantageously provide a very easy and simple way toelectropolish such devices to impart a high degree of smoothness in theelectropolished device while allowing substantially simultaneouslyelectropolishing of a plurality of such devices. Furthermore, byproviding a spiral cathode in an electropolishing container made from amaterial with low thermal conduction, the electrolyte solution mayremain stable for an extended time.

In one embodiment, an apparatus for electropolishing one or more stentsincludes a spiral cathode in an electropolishing container made from amaterial with low thermal conduction. The electrolyte solution mayremain stable for an extended time in such an apparatus. In a moredetailed embodiment, the apparatus includes two concentric spiralcathodes with the one or more stents, as anodes, placed therebetween,thereby providing additional cathode surface area. The pitch of thespiral can be varied in order to balance good agitation of theelectrolytic solution in the polishing container to ensure continuouselectrolyte concentration and composition and provision of a highsurface area of the cathode.

In another embodiment, an improved electrolytic solution comprising atleast dimethylsulfate for improved electropolishing of metallic medicaldevices, such as stents, is also described.

Referring to FIG. 1, there is shown an embodiment of an apparatus 100according to the disclosure. The apparatus 100 may include at least oneelongated member 11 in a downward orientation along a longitudinal axis.Each of the elongated members 11 may accommodate an electricallyconductive adapter 24 which may be capable of being removably affixed toand/or in electrical contact with a metallic stent 13.

With the at least one elongated member 11 immersed in electropolishingsolution 19 contained in a container 14, a tubular substantiallycontinuous spiral cathode 21 may be in close proximity with the at leastone elongated members 11. Each elongated member 11 may be substantiallyequidistant from the facing surface of the cathode 21. This may providea consistent field to each of the stents 13. The cathode 21 may beattached to a cathode conducting member 22. The at least one stent 13,as anodes, attached to the elongated member(s) 11 may all be inelectrical connection in series and/or in parallel with an anode currentconducting member 23. The cathode conducting member 22 and/or the anodeconducting member 23 may be connected to an electromotive force(“EMF”)-providing DC source (e.g., a battery) from which current and/orvoltage may be controlled by an appropriate controller. The entiresystem may be placed into a polishing container 14 made from materialwith a low thermal conduction. Suitable materials for the polishingcontainer 14 may include glass, ceramic, plastic, or other materials.

The polishing container 14 may contain an electrolytic electropolishingsolution 19 and/or may be placed in a double walled reaction container16. The polishing container 14 may be cooled with a cooling solution 15,such as ethanol or other suitable cooling solution. Using the polishingcontainer 14 made from material with low thermal conduction may reducewater condensation at the wall portions of the polishing containerexposed to, for example, air. Dilution of the electropolishing solution19 by water condensing out of the air may be reduced potentiallyresulting in the electropolishing solution 19 that may be stable and/orreliable and/or may provide constant polishing results. To facilitateagitation of the electropolishing solution 19 during theelectropolishing process, a stirrer 18, such as a magnetic stirrer maybe placed into the polishing container 14.

Examples of suitable stents for the stents 13 include, but are notlimited to, coronary and endovascular stents. Typical coronary and/orendovascular stents may vary in a range from about 7 to up to about 200millimeters in length with a diameter in a range of about 1 to about 12millimeters. However, stents of larger or smaller size may be suitablyaccommodated. The stents 13 may be made from high-strength medicalalloys, such as stainless steel, titanium alloys, nickel-titaniumalloys, tungsten or a tungsten alloy, tantalum or a tantalum alloy,niobium or a niobium alloy, cobalt-chromium alloys,cobalt-chromium-tungsten alloys, combinations of any of the foregoing,or another suitable metal or alloy.

In order to accomplish the electropolishing process, the one or morestents 13, which may all be substantially identical in length, diameter,design, or combinations thereof, may be placed on the one or moreelectrically conductive adaptors 24. The mounted stents 13 may beimmersed into the electropolishing solution 19. The temperature of theelectropolishing solution may be between about −20° C. and about 0° C.,between about −20° C. and about −10° C., or about −15° C. A voltage issupplied to the stents 13, as anodes, and the cathode 21 toelectropolish the stents 13 to the desired smoothness. Useful voltagemay be in the range of about 7 volts to about 40 volts, between about 10volts and about 30 volts, or between about 10 volts and about 20 volts.Voltage may be applied in about 20 second to about 60 second intervalsand, in some embodiments, in about 30 second intervals. However,voltages outside of these ranges may also be useful, depending upon thenumber of stents, electrolyte, and/or other design and/or processparameters.

It may be desirable for the electropolishing process to be performed instages. After one immersion in the electropolishing solution 19,typically lasting from about 20 to about 60 seconds, the stents 13 maybe removed from the electropolishing solution 19 and washed, typicallywith alcohol, water, nitric acid, or combinations thereof. Then, theelectropolishing may be repeated several times with each step followedby a rinse of the stents 13. Typically, a suitable polishing processwill include about three to about five iterations of theelectropolishing step. But more or fewer iterations may be suitable,depending upon the stents, electrolyte, voltage, other processvariations, or combinations thereof. Once the desired electropolishingis completed, the stents 13 may be removed from the electropolishingsolution and from the electropolishing apparatus 100, rinsed, andcontacted with a passivation solution to remove residualelectropolishing solution. The stents 13 are typically again rinsed andplaced in a bath to which ultrasound energy may be applied to completethe rinsing. A final rinse step may involve exposure for about 10minutes in an ultrasound bath at approximately room temperature.

Embodiments of an electrolytic solution for electropolishing one or moremetallic stents for use in the methods and apparatuses described aboveare also disclosed. The electrolytic solution for use in the methodsdescribed above comprises at least dimethylsulfate.

In some embodiments, the electrolytic solution may not includepolyethylene glycol, dimethylsulfate, and ethanol at the same time. Inother embodiments, the electrolytic solution includes polyethyleneglycol, ethanol, and dimethylsulfate. In other embodiments, theelectrolytic solution includes polyethylene glycol, dimethylsulfate,ethanol, and methanol.

In a further embodiment, the electrolytic solution includes from about25 to about 60 weight percent dimethylsulfate, from about 30 to about 40weight percent dimethylsulfate, from about 35 to about 39 weight percentdimethylsulfate, or about 37 weight percent dimethylsulfate. Such weightpercentages of dimethylsulfate are more typical when both ethanol andmethanol are present in the electrolytic solution.

In one embodiment, the electrolytic solution may further include atleast one additional component, such as at least one alcohol. Forexample, the at least one alcohol may be a polyol (e.g., polyethyleneglycol) and/or at least one alkyl alcohol (e.g., ethanol, methanol, orcombinations thereof). In an embodiment, the polyethylene glycol is PEG1000.

In a further embodiment, the electrolytic solution may include fromabout 0.1 to about 5 weight percent polyethylene glycol, from about 0.5to about 2 weight percent polyethylene glycol, or about 0.5 to 1 weightpercent polyethylene glycol.

In one embodiment, the electrolytic solution includes from about 15 toabout 50 weight percent ethanol, from about 20 to about 40 weightpercent ethanol, from about 25 to about 35 weight percent ethanol, fromabout 25 to about 30 weight percent ethanol or about 28 weight percentethanol. In some embodiments, the ethanol may be replaced with methanol,a mixture of ethanol and methanol, or other alkyl alcohol. In someembodiments, the balance of the electrolytic solution is made up ofmethanol.

In a more specific embodiment, the electrolytic solution includes fromabout 0.1 to about 5 weight percent polyethylene glycol, from about 0.5to about 2 weight percent polyethylene glycol, or from about 0.5 toabout 1 weight percent polyethylene glycol, with the polyethylene glycolbeing PEG 1000; from about 25 to about 60 weight percentdimethylsulfate, from about 30 to about 40 weight percent, from about 35to about 39 weight percent, or about 37 weight percent; from about 15 toabout 50 weight percent ethanol, from about 20 to about 40 weightpercent, from about 25 to about 35 weight percent, from about 25 toabout 30 weight percent, or about 28 weight percent; and a balance ofmethanol.

In another embodiment, the electrolytic solution includes from about 40to about 70 weight percent dimethylsulfate, from about 50 to about 60weight percent dimethylsulfate, from about 54 to about 58 weight percentdimethylsulfate, or about 56 weight percent dimethylsulfate. Such weightpercentages may be more typical in electrolytic solutions that includedimethylsulfate, polyethylene glycol, a balance of ethanol, and aresubstantially free of methanol.

In a more specific embodiment, the electrolytic solution includes fromabout 0.1 to about 5 weight percent polyethylene glycol, from about 0.5to 2 weight percent polyethylene glycol, or about 1 weight percentpolyethylene glycol, with the polyethylene glycol being PEG 1000; fromabout 40 to about 70 weight percent dimethylsulfate, from about 50 toabout 60 weight percent, from about 54 to about 58 weight percent, fromabout 55 to about 57 weight percent, or about 56 to about 57 weightpercent; and a balance of ethanol.

The following examples are presented for the purpose of illustration andare not intended to limit the disclosure and claims in any way.

Example 1

Four dry identical stents made from a high-strength medical alloy may beremovably affixed to the adapters of four elongated members. Whileagitating a electropolishing solution of polyethylene glycol (PEG 1000):dimethylsulfate: ethanol :methanol in a weight ratio of about1:59:44:54, (i.e., 0.6 weight percent polyethylene glycol (PEG 1000),37.3 weight percent dimethylsulfate, 27.9 weight percent ethanol and34.2 weight percent methanol), the stents are lowered on the apparatusinto the electropolishing solution. The positive lead from theelectrical source is attached to the apparatus and the magnetic stirrerin the electropolishing container is turned on to facilitate agitationof the electropolishing solution. When the cycle time has elapsed(depending on the size and type of stent), the stents are removed fromthe electropolishing solution and submerged in a container of ethanol.Each stent is moved while submerged. The stents are then re-immersed inthe electropolishing solution for another polishing cycle. The polishingcycle is repeated for four polishing cycles. The stents are removed fromthe adapters and placed into a purified water rinse for about 30seconds. The stents are then removed and placed in nitric acidpassivation rinse bath for 30 minutes. The stents are removed from thebath and placed in a purified water ultrasonic bath for about 10minutes. The stents are then removed from the bath, rinsed with alcoholand are dried with compressed air. The stents achieve a very high degreeof smoothness.

Example 2

Four dry identical stents may be removably affixed to the adapters offour elongated members. While agitating an electropolishing solution ofpolyethylene glycol (PEG 1000): dimethylsulfate:ethanol in a weightratio of about 1:59:44 (i.e., about 1 weight percent polyethylene glycol(PEG 1000), 57 weight percent dimethylsulfate, 42 weight percentethanol), the stents are lowered on the apparatus into theelectropolishing solution. The positive lead from the electrical sourceis attached to the apparatus and the magnetic stirrer in theelectropolishing container is turned on to facilitate agitation of theelectropolishing solution. When the cycle time has elapsed (depending onthe size and type of stent), the stents are removed from theelectropolishing solution and submerged in a container of ethanol. Eachstent is moved while submerged. The stents are then re-immersed in theelectropolishing solution for another polishing cycle. The polishingcycle is repeated for four polishing cycles. The stents are removed fromthe adapters and placed into a purified water rinse for about 30seconds. The stents are then removed and placed in nitric acidpassivation rinse bath for 30 minutes. The stents are removed from thebath and placed in a purified water ultrasonic bath for about 10minutes. The stents are then removed from the bath, rinsed with alcoholand are dried with compressed air.

The present disclosure may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the disclosure is, therefore,indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

1. A method of electropolishing metallic stents, the method comprising:a) affixing a stent on a respective one of one or more electricallyconductive adaptors of an apparatus, the apparatus comprising: at leastone elongated member having a longitudinal axis, the at least oneelongated member comprising one of the one or more electricallyconductive adaptors configured to be removably affixed to and inelectrical contact with the stent; an electrolytic solution; asubstantially continuous cathode configured to be located in closeproximity to the at least one elongated member when the least oneelongated member and the substantially continuous cathode are immersedin the electrolytic solution; a cathode current conducting memberattached to the substantially continuous cathode; an anode currentconducting member, wherein each of the one or more elongated members isconductively connected electrically with the anode current conductingmember; b) immersing the at least one stent in the electrolyticsolution; c) supplying a voltage difference between the cathode currentconducting member and the anode current conducting member; and d)removing the at least one stent from the electrolytic solution andrinsing with alcohol.
 2. The method according to claim 1, furthercomprising repeating acts b), c), and d).
 3. The method according toclaim 1, wherein the acts b), c), and d) are repeated three to fivetimes.
 4. The method according to claim 1, further comprising: e)removing the at least one stent from the apparatus; f) rinsing the atleast one removed stent; g) immersing the at least one rinsed stent in apassivation solution; h) removing the at least one passivated stent fromthe passivation solution and rinsing the at least one passivated stent;and i) placing the at least one rinsed and passivated stent in a liquidand applying ultrasound energy to the liquid.
 5. The method according toclaim 4, wherein the passivation solution comprises nitric acid.
 6. Themethod according to claim 4, wherein the ultrasound energy is applied tothe liquid at room temperature.
 7. The method according to claim 1,wherein the electrolytic solution comprises dimethylsulfate.
 8. Themethod according to claim 7, wherein the electrolytic solution furthercomprises at least one alcohol selected from the group consisting ofpropylene glycol, ethanol, and methanol.
 9. An electrolytic solutioncomprising dimethylsulfate.
 10. The electrolytic solution according toclaim 9, further comprising at least one alcohol selected from the groupconsisting of polyethylene glycol, ethanol, and methanol.
 11. Theelectrolytic solution according to claim 10, wherein the at least onealcohol is polyethylene glycol, and wherein the polyethylene glycolcomprises PEG
 1000. 12. The electrolytic solution according to claims 9,further comprising about 0.1 to about 5 weight percent polyethyleneglycol.
 13. The electrolytic solution according to claim 9, furthercomprising about 0.5 to about 1 weight percent polyethylene glycol. 14.The electrolytic solution according to claims 9, wherein thedimethylsulfate is present in an amount from about 25 to about 60 weightpercent.
 15. The electrolytic solution according to claim 9, wherein thedimethylsulfate is present in an amount from about 35 to about 39 weightpercent dimethylsulfate.
 16. The electrolytic solution according toclaim 9, further comprising about 15 to about 50 weight percent ethanol.17. The electrolytic solution according to claim 9, further comprisingbetween about 25 and about 30 weight percent ethanol.
 18. Theelectrolytic solution according to claim 17, further comprisingmethanol.
 19. The electrolytic solution according to claim 9, furthercomprising polyethylene glycol and ethanol.
 20. The electrolyticsolution according to claim 9, further comprising: wherein thedimethylsulfate is present from about 40 to about 70 weight percentdimethylsulfate; about 0.1 to about 5 weight percent polyethyleneglycol; and a balance of ethanol.
 21. The electrolytic solutionaccording to claim 9, further comprising: wherein the dimethylsulfate ispresent from about 25 to about 60 weight percent of the electrolyticsolution; about 0.1 to about 5 weight percent polyethylene glycol; and abalance of methanol.
 22. An apparatus for substantially simultaneouslyelectropolishing a plurality of metallic stents, the apparatuscomprising: a plurality of elongated members each having a longitudinalaxis, each of the plurality of elongated members comprising anelectrically conductive adaptor configured to be removably affixed toand in electrical contact with a metallic stent; an electrolyticsolution contained in a polishing container; a substantially continuousspiral cathode configured to be located in close proximity to each ofthe plurality of elongated members when one or more metallic stents andthe cathode are immersed in said electrolytic solution; a cathodecurrent conducting member attached to the substantially continuouscathode; and an anode current conducting member, wherein each of theplurality of elongated members is conductively connected electricallywith the anode current conducting member.
 23. The apparatus according toclaim 22, wherein the polishing container is made from materialexhibiting a low thermal conductivity.
 24. The apparatus according toclaim 22, further comprising: a second continuous spiral cathodeconfigured to be located in close proximity to each of the plurality ofelongated members when the plurality of elongated members and cathodeare immersed in the electrolytic solution; and a second spiral cathodecurrent conducting member attached to the second cathode.
 25. Theapparatus according to claim 24, wherein the spiral cathodes are tubularin shape and disposed substantially concentrically in the electrolyticsolution.
 26. The apparatus according to claim 22, wherein theelectrolytic solution comprises dimethylsulfate.
 27. A method ofelectropolishing at least one stent, comprising: immersing the at leastone stent in an electrolytic solution, wherein the electrolytic solutioncomprises dimethylsulfate; and electropolishing the at least one stentwhile the at least one stent is immersed in the electrolytic solution.28. The method of claim 27, wherein the electrolytic solution comprisesat polyethylene glycol, ethanol, and methanol.
 29. The method of claim27, wherein the electrolytic solution comprises at polyethylene glycoland ethanol.